Friction welding process

ABSTRACT

Friction welding process in which metallic workpieces are welded at end and side interface zones with substantially all flash squeezed radially inwardly into an opening in one of the workpieces at the axis of rotation.

United States Patent 1 Welch Dec. 11, 1973 FRICTION WELDING PROCESS [75]Inventor: Eugene E. Welch, Indianapolis, Ind.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Feb. 23, 1972 [21] Appl. No.: 228,705

[52] U.S. Cl. 29/4703, 228/2 [51] Int. Cl 823k 27/00 [58] Field ofSearch 228/2; 29/4703; 156/73 [56] References Cited UNITED STATESPATENTS 3,338,775 8/1967 Dawn et al 228/2 X Layd et al 29/4703 X Canady29/4703 X Primary Examiner.l. Spencer Overholser AssistantExaminer-Robert J. Craig Attorney-W. E. Finken et al.

[57] ABSTRACT Friction welding process in which metallic workpieces arewelded at end and side interface zones with substantially all flashsqueezed radially inwardly into an opening in one of the workpieces atthe axis of rotation.

4 Claims, 4 Drawing Figures FRICTION WELDING PROCESS This inventionrelates to friction welding and more particularly to a new and improvedprocess of frictionally welding metal workpieces together at end andside interface zones.

Prior to the present invention many different friction welding processesand techniques have been employed to frictionally weld metal rods andtubes to metallic workpieces such as a plate. With most of these priorart processes, the workpieces were joined only at a single engagedinterface zone with flash radially extruded outwardly. While welds madewith these prior processes have been entirely satisfactory in mostcases, they do not meet new and higher standards for increased loadrequirements particularly wherelarge torques are to be transmitted.Furthermore, the extruded flash often had to be removed by specialtooling and procedures during or after welding and this burdensome tasksubstantially added to the cost of the welds.

With this invention there is a new and improved friction welding processin which the end and side faces of a rod or tube are frictionally weldedto a plate member. Also in this invention special provision is made tocontrol the flash causing it to be squeezed radially inwardly toeliminate the need for flash trimming or removal.

In the preferred embodiment of this friction welding process a generallycylindrical recess is formed in one metallic workpiece whichdhas aninternal diameter only slightly greater than thefexternal diameter ofanother workpiece which may be a metallic tube or a solid metal rod witha flash receiving recess in the end thereof. The end portion of the tubeor rod is clamped in a chuck which is part of a known flywheel mass. Theflywheel mass is rotated to a predetermined rpm, the rotation mechanismdisengaged and the rotating workpiece inserted in the cylindrical recessof the stationary workpiece with an axial load applied thereto.Initially, in a welding cycle, the end of the rod frictionally engagesthe flat bottom of the cylindrical recess to frictionally heat thematerial of the engaged interface so that it plasticizes with little orno initial extrusion or flash. As this is taking place, heat energycauses the tubular workpiece to expand relative to the confining wallsdefining the cylindrical recess. This, expansion causes the side wallsof the workpieces to engage at a cylindrical and second interface. Oncontinued relative rotation of the second workpiece the second interfaceheats and plasticizes so that a continuous bond is formed which extendsfrom the engaged end interface up around the sides of the twoworkpieces. The rotation of the second workpiece is'stopped by thesolidification of the weld; that is, the plasticized bond solidifiesinto what may be descriptively termed as an around the corner frictionweld. The engaged interface acts as a seal so that the flash is squeezedinwardly into the recess formed in the metal rod or into the end of thetube. With a curled ring of flash formed inside of the tubularworkpiece, flash generally does not need to be removed; however, ifdesired a grinding tool may readily be inserted through the open end ofthe tube to the weld to mechanically grind and smooth the flash.

It is an object of this invention to provide a new and improved processof friction welding first and second workpieces at intersectinginterface zones.

lt'is another object of this invention to provide a new and improvedprocess for frictionally welding metallic workpieces together in whichrelatively rotating workpieces are frictionally engaged under apredetermined axial load at a substantially flat bottom interface and inwhich one of the workpieces radially expands relative to the otherworkpiece from the heat of friction as the bottom interface plasticizesinto full frictional engagement with a cylindrical side wall of theother workpiece to form a second interface which plasticizes to therebyproduce a continuous weld between the bottom and side interfaces ontermination of the relative rotation of said workpieces.

It is another object of this invention to provide a new and improvedfriction welding process in which the side and the bottom portions ofworkpieces are frictionally engaged and welded and in which all flash istrapped in an internal space provided within the engaged workpieces.

These and other features, objects and advantages 0 the invention willbecome more apparent from the following detailed description anddrawingin which:

FIG. 1 is a side elevational view in cross-section showing workpieces tobe welded together.

FIG. 2 is a view similar to FIG. 1, showing the workpieces broughttogether for frictional welding purposes.

FIG. 3 is a view similar to FIG. 2 showing the two workpieces afterbeing welded together by this friction welding process.

FIG. 4 is a cross-sectional view showing other types of workpieces beingwelded together utilizing the process according to this invention.

Turning now to the drawings in greater detail, there is shown in FIG. 1an annular steel plate 10 which is formed with a central cylindricalrecess 12 having a flat end surface 14 surrounded by an annular wall 16.The

recess 12 is dimensioned to closely receive the cylindrical end portion18 of an elongated steel tube 20. The tube 20 preferably has a flatforward surface or contact face 22 for fully engaging the flat surfaceof recess 12 for friction welding purposes.

The plate and tube are adapted to be loaded in any suitable frictionwelding machine such as a welder with flywheel drive for rotating oneworkpiece while the other is held stationary and with motor means foreffecting the engagement of the workpieces at an interface under anydesired load.

Using such a friction welding machine the tube 20 is rotated about axis21 to a predetermined speed sufficient for achieving a friction weld ofthese two parts. Then the machine is further activated so that the tube20 is moved axially and so that the end portion 18 enters the recess 12with the forward surface 22 of tube 20' frictionally engaging the flatsurface 14 on the stationary workpiece 10. With the workpieces engagedunder axial load the interface defined by these two surfaces rapidlyheats and becomes plasticized. While this is taking place the end 18 ofthe workpiece 20 radially expands relative to the internal diameter ofthe opening 12 so that its side wall frictionally engages thecylindrical side 16 of the recess 12. The interface zone defined bythese frictionally engaged side walls also rapidly heats to a plasticcondition forming a bond that fuses with the plastic bond at the forwardinterface zone.

After the plasticized bond has been formed the relative rotation of theworkpieces is stopped by the solidification of the weld, that is, thebond quickly solidifies to rigidly join the two'workpieces together. Thewelder is then unloaded and new workpieces are loaded for a secondwelding operation.

The upset pressure applied to the rotating workpiece during the weldcycle extrudes an annular ring of flash material 26 that is radiallyextruded inwardly from the tubular workpiece 20 as shown best in FIG. 3.There will be substantially no radial flash squeezed outwardly becauseof the sealing effect of the engaged sides of the workpiece. In FIG. 3,for example, the cylindrical edge 30 of the weld tapers; the contactingportions of the workpiece dispose outwardly the heat affected zone 32providing a seal substantially preventing the radial extrusion of flash.Any flash which may be extruded radially outwardly is generally minorand usually can be ignored or readily removed by suitable tooling.

FIG. 4 discloses a modification of the process involving the welding ofa solid cylindrical rod 34 and a fiat metallic plate 36. As shown therod 34 has a central counterbore 38 in one end thereof and the plate 36has a cylindrical recess 40 milled therein with a fiat bottom surface42. The diameter of the recess 40 is slightly greater than the diameterof the rod. The welding procedure is substantially the same as withplate and tube 20. The finished weld is shown in FIG. 4 with the flash44 extending radially inwardly from the heat affected zone 46 into thebore 38. Again the bond is between the engaged bottom and sideinterfaces providing a second example of around the corner frictionwelding.

The preferred embodiment of this invention described and illustrated inthis application can be modified to suit particular requirements. Thescope and limitations of this invention are set forth in the followingclaims.

I claim:

1. A process for friction welding metallic first and second workpiecestogether comprising the steps of providing a cylindrical end on saidfirst workpiece with an end opening surrounded by an annular end wall,forming a generally cylindrical pocket in said second workpiece with asubstantially fiat end face surrounded by a circular side wall,relatively rotating said workpieces, engaging said relatively rotatingworkpieces with a predetermined load to cause the workpieces to engageat an end interface so that the material of said workpieces at saidinterface will plasticize, allowing said first workpiece to radiallyexpand and frictionally engage the cylindrical wall of said secondworkpiece at a second interface, continuing the relative rotation ofsaid workpieces so that the material of said workpieces at said secondinterface plasticizes, further continuing said relative rotation untilthe plasticized material forms a continuous bond that encompasses saidfirst and second interfaces and relatively rotating workpieces arefrictionally engaged under a predetermined axial load at a substantiallyflat bottom interface and in which one of the workpieces radiallyexpands relative to the other workpiece from the heat of friction as thebottom interface plasticizes into full frictional engagement with acylindrical side wall of the other workpiece to form a second interfacewhich plasticizes to thereby produce a continuous weld between thebottom and side interfaces on termination of the relative rotation ofsaid workpieces.

2. A process for friction welding a first metallic workpiece having alongitudinally extending cylindrical wall and a laterally extending endsurface to a second metallic workpiece comprising the steps of forming arecess in a central portion of said second workpiece with a laterallyextending bottom surface for engaging said end surface of said firstworkpiece and with an annular side wall of a diameter slightly greaterthan the diameter of said cylindrical wall of said first workpiece,rotating said first workpiece relative to said second workpiece to apredetermined speed, moving one of said workpieces axially relative tothe other of said workpieces to engage said relatively rotatingworkpieces under load at a first interface formed by said laterallyextending end surface of said first workpiece and said bottom surface ofsaid second workpiece so that said workpieces frictionally heat andplasticize at said first interface, continuing said rotation of saidfirst workpiece so that relative expansion of said workpiece causes aportion of said cylindrical wall of said first workpiece to frictionallyengage the annular side wall of said recess of said second workpiece ata second interface and cause said second interface to frictionally heatand plasticize and coact with said plasticized first interface to form acontinuous bond that encompasses said first and second interfaces andallowing said continuous bond to solidify to thereby rigidly connectsaid workpieces on termination of the relative rotation thereof.

3. A process for friction welding a first metallic workpiece having alongitudinally extending cylindrical portion and a flat contact face toa second metallic workpiece comprising the steps of forming a recess insaid second workpiece with a flat end surface for engaging said contactface of said first workpiece and with an annular side wall having adiameter slightly greater than the diameter of the cylindrical portionof said first workpiece, providing a longitudinally extending passageextending through the contact face of said first workpiece, relativelyrotating said workpieces to a speed sufficient to cause the workpiecesto frictionally heat to a welding temperature when engaged under apredetermined load, applying a load to engage said workpieces at a firstinterface comprising said contact face and said end surface so that thematerial of said relatively rotating workpieces plasticizes in a firstzone, continuing said relative rotation until the differential expansionof said workpieces causes the cylindrical portion to contact the annularside wall of said recess at a second interface so that the material ofsaid workpieces plasticizes in a second zone, stopping the relativerotation of said workpieces so that the bond formed by the plasticizedmaterial of said workpieces includes both of said zones and so thatsubstantially all weld flash produced during welding is squeezed by theload into said longitudinally extending passage in said first workpiece.

4. A process for frictionally welding first and second metallicworkpieces together comprising the steps of forming a cylindrical recessin said second workpiece with a flat annular bottom and an annular sidewall, providing a first workpiece with a longitudinally extendingcylindrical part which has a diameter slightly less than the diameter ofsaid cylindrical recess and with a transversely extending contact faceat the end thereof, providing an opening in said first workpiece whichopens out of said contact face, relatively rotating said workpieces to aspeed sufficient to allow their frictional welding, engaging saidrelatively rotating workpieces under load with an end portion of saidcylindrical part of said first workpiece disposed within the cylindricalrecess formed in said second workpiece so that the contact face of saidfirst workpiece engages the friction and plasticizes in a second zone,continuing said relative rotation of said workpieces so that acontinuous bond is formed that includes both of said interfaces and sothat substantially all weld flash is extruded radially inwardly intosaid opening as said relative rotation terminates and said bond hardensto rigidly join said workpieces together.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pat 3 777.360DlI1bL ll-;.l27 3 Invent-or(s) Eugene E. Welch It is certified thaterror appears inthe above identified: patent and that said LettersPatent are hereby corrected as shown below:

; y y "I f Columns 1 and 2: the paragraph beginning with line 65 ofcolumn 1 through line 10 of column 2 should be inserted in column 2,between lines 16 and 17.

. Column 3, claim 1, lines 52 through 62, delete "relatively rotatingworkpieces are. .relative rotation of said workpieces" I and inserttherefor allowing said second interface to form 'a seal so that weldflash produced during welding is extruded 1 radially inwardly and intothe end opening insaid first workpiece Signed aha sealed this 6th day ofAugust 1974.

( SEA L) Attest: v I

MCCOY M GI BSON, JR. 0. MARSHALL DANN Attesting Officer Commissioner ofPatents

1. A process for friction welding metallic first and second workpiecestogether comprising the steps of providing a cylindrical end on saidfirst workpiece with an end opening surrounded by an annular end wall,forming a generally cylindrical pocket in said second workpiece with asubstantially flat end face surrounded by a circular side wall,relatively rotating said workpieces, engaging said relatively rotatingworkpieces with a predetermined load to cause the workpieces to engageat an end interface so that the material of said workpieces at saidinterface will plasticize, allowing said first workpiece to radiallyexpand and frictionally engage the cylindrical wall of said secondworkpiece at a second interface, continuing the relative rotation ofsaid workpieces so that the material of said workpieces at said secondinterface plasticizes, further continuing said relative rotation untilthe plasticized material forms a continuous bond that encompasses saidfirst and second interfaces and relatively rotating workpieces arefrictionally engaged under a predetermined axial load at a substantiallyflat bottom interface and in which one of the workpieces radiallyexpands relative to the other workpiece from the heat of friction as thebottom interface plasticizes into full frictional engagement with acylindrical side wall of the other workpiece to form a second interfacewhich plasticizes to thereby produce a continuous weld between thebottom and side interfaces on termination of the relative rotation ofsaid workpieces.
 2. A process for friction welding a first metallicworkpiece having a longitudinally extending cylindrical wall and alaterally extending end surface to a second metallic workpiececomprising the steps of forming a recess in a central portion of saidsecond workpiece with a laterally extending bottom surface for engagingsaid end surface of said first workpiece and with an annular side wallof a diameter slightly greater than the diameter of said cylindricalwall of said first workpiece, rotating said first workpiece relative tosaid second workpiece to a predetermined speed, moving one of saidworkpieces axially relative to the other of said workpieces to engagesaid relatively rotating workpieces under load at a first interfaceformed by said laterally extending end surface of said first workpieceand said bottom surface of said second workpiece so that said workpiecesfrictionally heat and plasticize at said first interface, continuingsaid rotation of said first workpiece so that relative expansion of saidworkpiece causes a portion of said cylindrical walL of said firstworkpiece to frictionally engage the annular side wall of said recess ofsaid second workpiece at a second interface and cause said secondinterface to frictionally heat and plasticize and coact with saidplasticized first interface to form a continuous bond that encompassessaid first and second interfaces and allowing said continuous bond tosolidify to thereby rigidly connect said workpieces on termination ofthe relative rotation thereof.
 3. A process for friction welding a firstmetallic workpiece having a longitudinally extending cylindrical portionand a flat contact face to a second metallic workpiece comprising thesteps of forming a recess in said second workpiece with a flat endsurface for engaging said contact face of said first workpiece and withan annular side wall having a diameter slightly greater than thediameter of the cylindrical portion of said first workpiece, providing alongitudinally extending passage extending through the contact face ofsaid first workpiece, relatively rotating said workpieces to a speedsufficient to cause the workpieces to frictionally heat to a weldingtemperature when engaged under a predetermined load, applying a load toengage said workpieces at a first interface comprising said contact faceand said end surface so that the material of said relatively rotatingworkpieces plasticizes in a first zone, continuing said relativerotation until the differential expansion of said workpieces causes thecylindrical portion to contact the annular side wall of said recess at asecond interface so that the material of said workpieces plasticizes ina second zone, stopping the relative rotation of said workpieces so thatthe bond formed by the plasticized material of said workpieces includesboth of said zones and so that substantially all weld flash producedduring welding is squeezed by the load into said longitudinallyextending passage in said first workpiece.
 4. A process for frictionallywelding first and second metallic workpieces together comprising thesteps of forming a cylindrical recess in said second workpiece with aflat annular bottom and an annular side wall, providing a firstworkpiece with a longitudinally extending cylindrical part which has adiameter slightly less than the diameter of said cylindrical recess andwith a transversely extending contact face at the end thereof, providingan opening in said first workpiece which opens out of said contact face,relatively rotating said workpieces to a speed sufficient to allow theirfrictional welding, engaging said relatively rotating workpieces underload with an end portion of said cylindrical part of said firstworkpiece disposed within the cylindrical recess formed in said secondworkpiece so that the contact face of said first workpiece engages thebottom of said cylindrical recess at a first interface, applyingsufficient load to cause said relatively rotating workpieces tofrictionally heat and plasticize in a zone including the engagedinterface, continuing said relative rotation so that the end portion ofsaid first workpiece radially expands relative to said second workpieceand directly contacts the annular side wall thereof to provide a secondinterface that is heated by friction and plasticizes in a second zone,continuing said relative rotation of said workpieces so that acontinuous bond is formed that includes both of said interfaces and sothat substantially all weld flash is extruded radially inwardly intosaid opening as said relative rotation terminates and said bond hardensto rigidly join said workpieces together.